andyscotland

I noticed that, also that even the company chief execs & people talking about their products seemed to have no "charisma" by modern standards: no way anyone getting interviewed about their work would get away with being that dry these days.

Oh yeah that bit had me on the edge of my seat waiting for it to all avalanche off the roof with him on top! Even knowing that they'd probably have cut that bit of footage out of required 🤣

One option for that is to use a double top plate. Build the panel on the ground with a single top plate with a good length of excess membrane overhanging the top. Swing it up & position it, then slide the second top plate into the gap between the panel and the overhanging membrane (so you end up with the membrane behind and over the top - then just cut off the excess). You can insert a couple of packers between the two top plates if needed get a tight fit. If the height is still too low for that you can also use a double sole plate. Fix it to the floor, swing the panel up beside it, then lift it on, then do the top plate trick as above. This obviously means having to lift the weight of the whole stud wall although you could build it in sections if necessary. This does of course increase the timber fraction/reduce insulation of the wall slightly.

I wasn't necessarily suggesting using them. The downside IMO is it's harder to get a good airtight/vapour-tight seal between boards. It's also harder to fix things to them - most plasterboard fixings assume a cavity behind the board, and will be harder/impossible to get them to spread out properly if the board is backed by insulation. Plus removing/moving things on plasterboard leaves a mess. If you want a tool wall/cleats etc then OSB or ply would give you a lot more flexibility. Yes, I suspect it will be.

I think you do need a DPM (or at least DPC strips between the timber and the brick) as it is drawn, assuming this is a single skin wall. Unless you do this: The other option would be to use a continuous layer of PIR on 25mm roofing battens on DPC strips, like this detail for eco-liner https://www.insulationbee.co.uk/72-5mm-ecotherm-eco-liner-rigid-pir-dry-lining-insulated-plasterboard-for-fix-and-dab-applications but a second layer of battens over the PIR (screwed through to the battens behind) to carry the OSB. This has fewer PIR joints to cut & foam, so may be easier to build and have less thermal bridging. Also fewer penetrations of the VCL (the battens only need fixed every 500mm or so). And gives you a service cavity for any wiring etc if you care about hiding that away. Bear in mind that PIR is efficient for heat insulation but not particularly effective for noise insulation: if that's your priority then a detail based on acoustic fibre or cellulose would be worth exploring.

This was brilliant, thanks for posting! I enjoyed the Glazier climbing up to the conservatory roof on some sort of trestle with large pane of glass in one hand and cigarette in the other 🤣 Also the idea that we'd all have electric vehicles and could charge them at night from our personal gas generators. And Valerie Singleton being presented with the programmable day/night thermostat and asking if people would have to go on a course to use it. But my favourite moment had to be when they showed what looked like it might be a wood burning stove in the living room before explaining it was a coal-fired boiler which would be useful in 2000 due to the limited availability of North Sea Gas, then later noted that someone would probably invent a more convenient way of feeding the coal in. 🤣

First question would be roughly where are you, are you in a conservation area or similar? The drawings mention "conservation style roof light" which (together with the appearance of the building) suggests you might be in an area with sensitivities around planning permission. My hunch would be that if they did work not that long ago and only expanded the rear dormer, that could well be because they knew they wouldn't get permission to extend on the side facing the street...

Bear in mind that a company can only reclaim input VAT that is related to trading & in turn to output VAT (slight simplification). If your company is supplying services to a participator in the company (e.g. director/shareholder) then it would likely need to do so at a reasonable "arms length" commercial rate e.g. by making a profit on the goods/services it is re-selling. Otherwise you get into things like deemed self-supply for VAT and payments in kind for other taxes. But if you pay your company a profit element on the job, you will not be able to get it back out again without paying dividend/corporation/PAYE tax (assuming your other income is above the relevant thresholds). There are ways to run things through a company that can be effective, but it needs to be carefully considered in the specific circumstance and would often be sensible to take professional advice. It's not a quick win for making small savings IMO.

@nod what do you do for substrate/tanking for the microcement: can it be applied over the impey waterguard you mentioned the other day?

The other difference (that is implied but not explicit in the earlier posts) is that Building Control is done entirely by the local authority covering your area. The English/Welsh option to use a private BCO does not exist.

To update - SIG no longer supply these, spoke to a helpful person at their Newcastle depot (after trying Scotland) who said that since the blown-in install now requires certification, the installers are all part of one or other manufacturer's official carded installer network and as part of that source materials direct from the manufacturer. My usecase is to pour into the lath & render/plaster box above a bay window (which currently contains no insulation of any kind). And also to pour into a small section of cavity wall that is now between the house & extension, mostly just to prevent airflow causing a thermal bridge from the cold loft down through the cavity. He suggested Vermiculite, but I'm not wild about that from a moisture / damp point of view (and the lambda is fairly poor). I'm leaning towards just buying fire rated white bean bag beads - they will be a lot better than status quo, and probably not going to get enough extra benefit from graphite to justify the cost of collection/delivery from Nottingham for what I need.

Oh yeah in that case definitely just redo it. You will probably get at least a bit of beer money if you take the cable to a local scrapyard.

If the extension is otherwise not being touched (no plastering, painting etc) then I would start by getting your electrician to inspect & test that part of the installation. PVC cables post the mid-70s that were properly installed and haven't been continuously running at high load can have a very long service life. If the insulation resistance and continuity is "as new", there's no visible damage or deterioration at terminals, and they meet modern requirements (e.g. have a CPC to lighting outlets) then personally I'd consider leaving that part of the installation as-is, at least until you're doing any major renovation/redecorating of the extension. But you will need your electrician to help you make that call both for their experience & knowledge in assessing the existing wiring and because they'll obviously ultimately have to sign off the decision. Do you already have an electrician lined up? Make sure you do before you start, they will likely want to agree parameters for the bits you're doing and e.g. things like the overall electrical design/cable sizing, locations of wiring routes etc. There are different rules for what you can/can't do in different parts of the UK but ultimately you'll need your electrician to be comfortable with (and clear on) exactly what they are being asked to certify.

No such thing as Part P in Scotland. The legal requirement is to be "competent" - however some (most?) councils seem to interpret that as "member of an industry body e.g. SELECT/NICEIC/ECA etc" and are firm on that view. Unfortunately that's a challenge as a DIY person, IMO best you can hope for is someone who will agree to split the work with you and sign it off at the end.

Welcome back, I certainly remember you! My project is still plodding on slowly, I'm edging towards the finish but life/other mini projects keep getting in the way. I was probably saying that last time you were here 🤣

I would never assume a cable can't be cut. Sooner or later someone will want to lift the slabs / dig out a weed / make some change. If it isn't steel wire armoured cable (and the second photo of it pvc taped into a terminal block looks like it isn't) then it's not compliant or safe. You could, however, use it for 12V if it's easier to change the supply and lamps than the cable. You'd need to check the cable conductors are thick enough for the load you want to supply : at lower voltage it takes more current to supply the same number of watts and this means the resistance of the cable becomes more important. There should be a cable sizing printed/embossed somewhere on the outer sheath although this may have come off if it's been outdoors a while.

@Wolfman310 ah that is a shame!

I'd read it to mean that the 100A RCD and heater RCBOs were all in the same board, so swapping for a 100A MCB wouldn't affect cable protection on the incomer (there might of course need to be something at whatever upstream supplies the heating DB as you say, depending on the cable). The more likely complication would be if it's a split load board, or a board manufactured and supplied with an RCD main switch, as that can then get into issues with modifying a tested assembly. Like you say, lots of variables easiest assessed with the electrician's eye on site - hopefully not followed by the electrician's sucking breath through teeth 🤣

@Redbeard thanks, I'll try SIG. Scotland is probably achievable for me to collect myself (I have a Citroen Berlingo which is pretty good for volume) - certainly more achievable than Nottingham!

Good point, I'd misread that as an RCBO. Yes if it's an RCD it will need a 100A overcurrent protective device in series though I think that could be upstream or downstream. To be fair if the individual circuits are on RCBO and are the only thing in the CU then you could (and perhaps should for selectivity) just swap the 100A RCD for an MCB which would also solve that issue.

@Wolfman310 could I ask how you got the beads to you? Polypearl have been very helpful but they can't do delivery or palletising as they only deliver bulk in their own transport. So it has to be collection from Nottingham as individual 10ft³ bags. Unfortunately due to the size of the bags I'm getting fairly ludicrous quotes for couriers to collect and bring to Edinburgh : 10 bags is ~£1,200 from the parcel courier comparison sites. Man & van sites are coming in around ~£300-£400 - better, but still fairly prohibitive... 😬

"earth fault loop impedance" is the technical term for "wire impedance" - e.g. (in very simplified terms) the resistance of the loop of cable from the live on the generator at the power station to the end of the circuit and back through the earth to the generator. This resistance/impedance determines the amount of current that can flow through a dead short from live to earth. The Earth Fault Loop Impedance is therefore one of the factors governing the size of the protective device : as you say it has to be low enough that a dead short will allow enough current to flow that the breaker will trip within the required disconnection time for the type of circuit. Hence as you have correctly understood, the electrician is saying he needs to measure the earth fault loop impedance at the far end of each circuit before he can confirm that it's appropriate to change the overcurrent protective device (as the limit for a 20A breaker is lower than that for a 16A breaker, and indeed the limit for a type C is lower than for a type B). This does sound like it is due to the cold resistance (and therefore inrush current) of the circuit. If there is a single heater per circuit then there's not a lot you can do other than change the type/rating of the protective device or put an inrush limiter in front of the heater. The ratings of the protective devices do not of themselves necessarily equal the maximum demand of the installation. BS7671 does not provide any mandatory method for calculating maximum demand : it is up to the designer to use their expertise to make a reasonable assessment. If you have 6 x 3kW heaters on fixed wiring with no other appliances connected (and no sockets in the circuits) then your maximum demand is 18kW = 78 Amps at UK nominal voltage (between 71-83 amps on a supply within the voltage tolerance range). This is without applying any diversity, which probably wouldn't be appropriate in this situation. Changing the protective devices doesn't in any way change the maximum demand of the heaters. Therefore, it's entirely reasonable to size the protective device for the demand, current carrying capacity and loop impedance of each individual circuit. It is not automatically a problem to have breakers adding up to 120A downstream of an overall 100A breaker. Of course, you may find that if you make each individual breaker big enough to carry the inrush current, you move the problem upstream and end up with the combined inrush now tripping the 100A protective device. This however could be managed by adding control gear to switch one or two heaters slightly on after the others. 2.5mm² T&E is rated for 23A in conduit/trunking on a wall surface, 27A clipped direct to the surface. If the cable is buried / passes through or under insulation at any point, or is bunched with others / at a nonstandard ambient temperature this will reduce those ratings. So from that perspective a 20A RCBO would likely be fine for the current carrying capacity of the cable.

The big challenge would likely be demonstrating that the VAT reclaim on the materials was genuinely for the purpose of trade. That would imply that you would need an arms length transaction on commercial terms for the installation. The claim that it was a show home / marketing expenditure would be very hard to evidence if you did not subsequently end up making any sales to anyone else. You might be able to argue that a discounted rate was justified, but that would almost certainly need to include at least some labour costs as well as cost of raw materials. You then have the challenge that the labour fees are in the company and can't get out of there without being taxed on some level. Is probably the wrong question, because the boot is largely on HMRC's foot. With most tax things, it's usually on you to prove you've done things right rather than on them to prove you haven't. The right question is therefore likely "If HMRC query my VAT reclaim, can I produce strong enough evidence to convince them I am genuinely intending to trade, and how much time / professional advice might I require to win that argument?". If HMRC think it "smells a bit off" then the likely outcome is they raise an assessment and challenge you to appeal that at Tribunal if you think they're wrong. It's very unlikely to be cost effective to go down that route.

@joe90 is correct that the special self-build VAT reclaim is only for standalone homes - it wouldn't cover a garden office or any property that can't be sold as a separate home (e.g. it wouldn't cover a "granny flat" in the garden either). If it was for a VAT registered business it might be possible to claim the VAT on the VAT return if the building was built entirely for business purposes, and will be used entirely for business purposes for a long period (10 years, I think). However this would require clear evidence and might also mean there is Capital Gains Tax to pay if/when the house is eventually sold. There are many pros, cons and complexities so this should all be discussed with an accountant. Technically, there is no top rate if you can demonstrate a reasonable calculation from shares of the utility bills and similar costs according to the portion of time used for business. However if you claim more than the HMRC flat rates (which they offer as a concession to simplify life for taxpayers and themselves) you can expect them to be interested in how you got your figures. It's not often worth going above their rates as by the time you have the hassle of calculating a fair figure you probably won't make much. However for a garden office it might be if t was used almost exclusively for business (but make sure you show some private/domestic use to avoid Capital Gains Tax) and e.g. has standalone electric heating that you can easily get a usage figure for.

I guess maybe @SteamyTea was thinking regs might be different, but this is just BS7671 which applies UK wide (not France though 🤣). I'm not sure why the electrician didn't like Wagos if they were in a proper containment (other than that some people don't like new things). When installed per manufacturer's instructions in a wagobox they are certified for use even in a totally inaccessible location (unlike anything with screw terminals). And are very hard to get wrong (again unlike anything with screw terminals). They do need to be in a proper box to provide protection for the unsheathed cables and strain relief, among other things, and the cable tie to hold the box closed is also important. I would definitely use a wagobox to repair that damaged section, ultimately even if it's not the cause - and it could well be - it needs to be repaired anyway. Hard to see from the photos how far it is to the junction box, if it's not too far best/cheapest bet is probably just one wagobox and then replace the whole section to the junction box. Alternatively get 2 boxes and just splice in a short replacement section. Make sure the cable you use matches or exceeds the size of the existing (I'd assume 1.5mm² will be fine, but check). Unless you have a spare bit of suitable old cable lying around for the repair you are going to have different core colours in the replacement section. Old red = Brown, Old black = Blue. You should therefore also have a label like this at the origin (you can make your own) - not that there's really any electricians out there who aren't well aware of the harmonised colours by now! Technically speaking as this is a repair to the fixed wiring it is Minor Electrical Works and should be done by a competent person, properly tested (with calibrated test equipment) & documented.